The **VRE202M** is a high-precision, low-noise precision voltage reference. It is primarily used in high-resolution data conversion systems, scientific instrumentation, and medical equipment where absolute accuracy and stability are critical. --- ### 1. Key Technical Specifications The VRE202M is part of a series known for its exceptionally low temperature coefficient and long-term stability. | Parameter | Typical Value / Range | | :--- | :--- | | **Output Voltage** | +2.500 V | | **Initial Accuracy** | ±0.25 mV (Grade M) | | **Temperature Coefficient** | 0.6 ppm/°C (Max) | | **Input Voltage Range** | 13.5V to 22.0V | | **Operating Temperature** | -55°C to +125°C | | **Noise (0.1Hz - 10Hz)** | 1.5 µVp-p | | **Package Style** | 20-Terminal LCC or 14-pin DIP | --- ### 2. Internal Electronic Architecture The device utilizes a sophisticated internal design to achieve its high performance: * **Zener Diode Base:** It typically uses a buried (sub-surface) Zener diode. Buried Zeners are inherently quieter and more stable than surface Zeners or Bandgap references. * **Laser Trimming:** During manufacturing, the internal thin-film resistors are laser-trimmed to achieve near-perfect initial accuracy and to compensate for temperature drift. * **Heater Control (In some variations):** Many high-end VRE series parts include an internal heater circuit to maintain a constant die temperature, though the 202M focuses on high-stability materials to achieve its low drift without high power consumption. --- ### 3. Application Circuitry To implement the VRE202M correctly, specific external components are required to ensure the output remains stable and noise-free. ```c // Typical Connection Diagram Concept [V_IN (15V)] ----> [Pin 2: VCC] [Pin 8: V_OUT] ----> (2.500V Output) [GND] ----> [Pin 4: Ground] /* Design Notes: 1. Place a 0.1uF ceramic capacitor close to the VCC pin. 2. Avoid heavy capacitive loading on the output to prevent oscillation. 3. Use a star-grounding technique to minimize trace resistance errors. */ ``` --- ### 4. Comparison of Grades The "M" suffix in VRE202M denotes the performance grade and temperature range. 1. **VRE202C:** Commercial grade (0°C to +70°C). 2. **VRE202I:** Industrial grade (-40°C to +85°C). 3. **VRE202M:** Military/High-Rel grade (-55°C to +125°C) with the tightest stability specifications. --- ### 5. Common Use Cases * **A/D and D/A Converters:** Providing the reference voltage for 18-bit to 24-bit converters. * **High-Precision Calibration:** Standards for portable calibration equipment. * **Aerospace Electronics:** Reliable performance in extreme temperature fluctuations.